Numerous systems exist for automated, remote monitoring of various appliances, including electric utility meters and the like. For instance, systems exist that couple utility meters to remotely located databases via the wired Public Switched Telephone Network (“PSTN”) so that the meters can be more efficiently and cheaply read remotely. Typically, such meter reading systems couple a database to a gateway that interfaces with the meter and, in many cases, other devices in a particular facility or portion thereof. These systems, however, are generally one way, sending data from the meter to the central processor.
Moreover, even when the system provides for two-way or duplex data communication that allows commands and other data to be down or up loaded to or from the gateway, a complete call must be made between the central processor and the gateway. Such calls are expensive, since they involve the full architecture of the PSTN in delivering the data, even when the amount of data delivered is relatively small. Also, the data or commands must be sent to or from a relatively intelligent central processor to which few persons will have access. This means, for instance, that customers at whose premises gateways are located cannot themselves send data (including commands for devices within the premises) to the gateway via the PSTN.
Systems exist that use short bursts of radio transmission to control and receive data from remote power distribution control terminals. For instance, a company called ITRON owns a U.S. Pat. No. 5,475,867 to Blum on such a system, albeit a system that uses supplemental controllers for expanding the fairly limited geographical range of the basic system. This system, however, would be expensive to deploy and operate since an essentially new architecture would need to be deployed.
Several companies, such as CellNet Data, Greenland and possibly ITRON, are trialing meter reading systems that use two-way paging, which provides broader geographic coverage. While such a system eliminates the trouble and expense of setting up a separate call each time data must be up or downloaded, paging messages provide limited payload for data, thereby limiting the potential for controlling and updating the gateway. Also, it is unclear whether such systems will allow users to send data and commands to or receive data from the gateway directly and without the need to go through a central processor or control center, which limits the flexibility of the system for users wishing to receive data about their facilities and remotely control various devices at the facility.